docstr: Train the model with train data.
  
  :return: predicted result.
docstr_tok: ["Train","the","model","with","train","data",".",":","return",":","predicted","result","."]
code: def fit(self, **kwargs):
      """
      Train the model with train data.
  
      :return: predicted result.
      """
  
      # Need to preprocess params as pytorch_ray_estimator does.
      #
      # ...
      # self._train_epochs(**kwargs)
      pass
  
imports: from bigdl.orca.learn.ray_estimator import BaseEstimator
  from bigdl.orca.ray import OrcaRayContext
  from bigdl.orca.data.file import enable_multi_fs_save, enable_multi_fs_load
  import io
  import torch
  import ray
  from ray.exceptions import RayActorError
  from abc import abstractmethod, ABCMeta
  from bigdl.orca.learn.pytorch.utils import find_free_port, check_for_failure
  from bigdl.orca.learn.utils import get_driver_node_ip
  from bigdl.dllib.utils.log4Error import invalidInputError, logging
  from typing import Dict
label_desc: Use image node_id 2 for calling the BaseRayEstimator obj's underlying member method code with example usage: obj.fit() without return types